Patent GB-749576-A (GB)
Title: Improvements in or relating to hydraulic presses for working metals
IPC: B21C23/21
Filed: 1952-06-13
Abstract: 749,576. Extruding. FIELDING & PLATT, Ltd., ROWLES, R. V., GOWING, B. T., and CRITTALL-LUXFER, Ltd. Feb. 2, 1954 [June 13, 1952], No. 15011/52. Class 83 (4). [Also in Group XXIX] A hydraulic press for extruding a tubular metal case open at one end, comprises an extruding punch 13 carried by a main ram 5, hydraulic means for holding the ram in an inoperative position and for releasing the ram to enable the full power available for effecting extrusion to move the ram and its punch, a billet container 16 movable in the axial direction of the ram, a fixed billet support 19 extending into the bore of the container, and hydraulic means 17 for moving the container from an inoperative position in which the billet support 19 extends substantially fully through the container bore to an operative position in which it extends only slightly into the bore and permits a billet to be positioned therein. A pair of rams 17 carry differential pistons 34 which are constantly open to pressure liquid on their lower surfaces through pipes 35, 23 from a hydraulic accumulator 21. The upper surfaces of the pistons 34, which are of greater area than their lower surfaces, may be supplied with pressure liquid through a two-way valve 38 and pipes 36, 37 so as to move the container 16 to its lowest position. A billet is then loaded on to a fixed support pin 19, projecting into the container, and the valve 38 is opened to exhaust whereby the container is raised to its upper position where it is centred by fixed projections 62, Fig. 2 (not shown), which engage within an annular recess 50 in the container. The main ram 5 carries a differential piston 4 which is continuously open on its upper surface to pressure liquid through a pipe 20. The lower surface of piston 4, whose area is greater than the upper surface, is supplied with pressure liquid through a two-way valve 24 for raising the ram. The piston 4 carries an extension rod 7 having a cylinder 8 co-operating with a fixed piston 9 supplied with pressure liquid through a two-way valve 26 and pipe 27. When pressure is supplied to the cylinder 8 and to both the upper and lower surfaces of the piston 4, the ram 5 is lowered to perform an approach stroke whereby the punch 13 engages the billet. The valve 24 is then opened to exhaust whereby the punch is forced into the billet to extrude it backwardly. The valve 26 may have an adjustable lift for varying the speed of the approach stroke and the valve 24 may have an adjustable lift for varying the speed of the extrusion stroke. A further valve 28 operated by a differential piston 31 may be used to supply liquid more quickly to the cylinder 8 during the approach stroke. When the ram is raised by supplying pressure liquid to the underside of the piston 4, the valve 28 is closed automatically by pressure acting through a pipe 33. A stripper plate 14 removes the extruded casing from the punch during its upstroke. The valves 24, 26, 38 may be operated by electromagnetic, hydraulic or pneumatic means. The container has a liner 49, Fig. 2 (not shown). Specification 749,571 is referred to.